Kinetics and mechanism of singlet oxygen-dominated peroxymonosulfate activation over zeolitic imidazolate framework-L-derived cobalt–nickel layered double hydroxide for rhodamine b degradation

Zeolitic imidazolate framework-L (ZIF-L)-derived cobalt–nickel layered double hydroxide (CoNi-LDH) nanosheets are developed as a heterogeneous activator of peroxymonosulfate (PMS) for Rhodamine B (RhB) degradation. The optimized CoNi-LDH/PMS system achieves 99% RhB removal within 12 min along with an apparent rate constant ( k obs ) of 0.55 min −1 , while total organic carbon removal reaches approximately 34% at 12 min. The catalyst also retains activity toward several representative organic contaminants, during five reuse cycles, and in tap and lake water matrices. Quenching experiments, electron paramagnetic resonance, nitroblue tetrazolium probing, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy collectively indicate that PMS activation is dominated by a singlet oxygen ( 1 O 2 )-mediated non-radical pathway, with radical species making minor contributions. The results further suggest that Co/Ni redox cycling promotes PMS activation, while lattice-oxygen-related surface changes would participate in interfacial electron transfer. This study highlights a ZIF-L-derived bimetallic LDH architecture that couples rapid PMS activation with preferential 1 O 2 generation, and provides a basis for further evaluation in complex water matrices.